U.S. patent application number 11/905895 was filed with the patent office on 2008-02-07 for cooling device capable of reducing thickness of electronic apparatus.
Invention is credited to Masuo Ohnishi, Atsuko Tanaka.
Application Number | 20080030948 11/905895 |
Document ID | / |
Family ID | 39028938 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080030948 |
Kind Code |
A1 |
Tanaka; Atsuko ; et
al. |
February 7, 2008 |
Cooling device capable of reducing thickness of electronic
apparatus
Abstract
A printed circuit board unit with a cooling device includes a
printed circuit board; a ventilation fan including blades rotating
around a rotation axis intersecting the printed circuit board; a
housing wall standing from a surface of the printed circuit board
at a periphery of the ventilation fan; an inlet defined in the
printed circuit board inside the housing wall and located under the
blades of the ventilation fan; and an outlet defined in the housing
wall to open in parallel with the surface of the printed circuit
board. An electronic apparatus is also provided which further
includes an electronic component mounted on the printed circuit
board.
Inventors: |
Tanaka; Atsuko; (Kawasaki,
JP) ; Ohnishi; Masuo; (Kawasaki, JP) |
Correspondence
Address: |
KRATZ, QUINTOS & HANSON, LLP
1420 K Street, N.W.
Suite 400
WASHINGTON
DC
20005
US
|
Family ID: |
39028938 |
Appl. No.: |
11/905895 |
Filed: |
October 5, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11369480 |
Mar 6, 2006 |
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11905895 |
Oct 5, 2007 |
|
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|
11120979 |
May 4, 2005 |
7019970 |
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11905895 |
Oct 5, 2007 |
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|
10664933 |
Sep 22, 2003 |
6909604 |
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11120979 |
May 4, 2005 |
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10096509 |
Mar 13, 2002 |
6665181 |
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10664933 |
Sep 22, 2003 |
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Current U.S.
Class: |
361/688 |
Current CPC
Class: |
G06F 1/203 20130101 |
Class at
Publication: |
361/688 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 17, 2001 |
JP |
2001-281683 |
Claims
1. A printed circuit board unit with a cooling device, comprising:
a printed circuit board; a ventilation fan including blades
rotating around a rotation axis intersecting the printed circuit
board; a housing wall standing from a surface of the printed
circuit board at a periphery of the ventilation fan; an inlet
defined in the printed circuit board inside the housing wall and
located under the blades of the ventilation fan; and an outlet
defined in the housing wall to open in parallel with the surface of
the printed circuit board.
2. The printed circuit board unit with the cooling device according
to claim 1, further comprising: an electronic component mounted on
the printed circuit board; and an electrically conductive wiring
pattern extending over the surface of the printed circuit board
inside the housing wall and connected to the electronic
component.
3. The printed circuit board unit with the cooling device according
to claim 2, further comprising a radiation fin connected to the
electrically conductive wiring pattern.
4. The printed circuit board unit with the cooling device according
to claim 3, further comprising an electronic component mounted on
the printed circuit board inside the housing wall.
5. The printed circuit board unit with the cooling device according
to claim 1, further comprising: a ceiling wall connected to an
upper end of the housing wall and extending along a datum plane
parallel to the surface of the printed circuit board; and an inlet
defined in the ceiling wall.
6. The printed circuit board unit with the cooling device according
to claim 5, further comprising: an electronic component mounted on
the printed circuit board; and an electrically conductive wiring
pattern extending over the surface of the printed circuit board
inside the housing wall and connected to the electronic
component.
7. The printed circuit board unit with the cooling device according
to claim 6, further comprising a radiation fin connected to the
electrically conductive wiring pattern.
8. The printed circuit board unit with the cooling device according
to claim 7, further comprising an electronic component mounted on
the printed circuit board inside the housing wall.
9. The printed circuit board unit with the cooling device according
to claim 1, further comprising an electronic component mounted on
the printed circuit board inside the housing wall.
10. An electronic apparatus comprising: a printed circuit board; an
electronic component mounted on the printed circuit board; a
ventilation fan including blades rotating around a rotation axis
intersecting the printed circuit board; a housing wall standing
from a surface of the printed circuit board at a periphery of the
ventilation fan; an inlet defined in the printed circuit board
inside the housing wall and located under the blades of the
ventilation fan; and an outlet defined in the housing wall to open
in parallel with the surface of the printed circuit board.
11. The electronic apparatus according to claim 10, further
comprising: an electronic component mounted on the printed circuit
board; and an electrically conductive wiring pattern extending over
the surface of the printed circuit board inside the housing wall
and connected to the electronic component.
12. The electronic apparatus according to claim 11, further
comprising a radiation fin connected to the electrically conductive
wiring pattern.
13. The electronic apparatus according to claim 10, further
comprising an electronic component mounted on the printed circuit
board inside the housing wall.
14. The electronic apparatus according to claim 9, further
comprising: a ceiling wall connected to an upper end of the housing
wall and extending along a datum plane parallel to the surface of
the printed circuit board; and an inlet defined in the ceiling
wall.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of application Ser. No. 11/120,979,
filed May 4, 2005, now U.S. Pat. No. 7,019,970; which is a
divisional of application Ser. No. 10/664,933, filed Sep. 22, 2003,
now U.S. Pat. No. 6,909,604; which is a divisional of application
Ser. No. 10/096,509, filed Mar. 13, 2002, now U.S. Pat. No.
6,665,181, and claims the benefit of foreign priority of JP
2001-281683, filed Sep. 17, 2001, the entire disclosures of which
are hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a printed circuit board
unit with a cooling device in general incorporated within an
electronic apparatus such as a portable digital assistant (PDA), a
notebook personal computer, and the like. In particular, the
invention relates to a printed circuit board unit comprising a
printed circuit board, a ventilation fan rotatable around the
rotation axis intersecting the printed circuit board, and a fan
housing accommodating the ventilation fan.
[0004] 2. Description of the Prior Art
[0005] As disclosed in Japanese Patent Application Publication
P2000-77877A, a so-called fan unit includes a fan housing
accommodating a ventilation fan rotating around the rotation axis.
When the ventilation fan rotates, air is allowed to flow in the
centrifugal direction of the rotation axis. The fan housing serves
to guide the air toward the outlet. The air is discharged out of
the outlet. At the same time, air surrounding the fan housing is
introduced into the fan housing through the inlet. The inlet is
defined to face the surface of the printed circuit board. When the
air is sucked into the fan housing, air is allowed to flow along
the surface of the printed circuit board. In general, a number of
electronic components are mounted on the surface of the printed
circuit board. The respective electronic components protrude from
the surface of the printed circuit board, so that the electronic
components hinder a smooth flow of the air. The turbulence in the
air is supposed to constrain the ventilation fan from sucking the
air into the fan housing. The suction quantity of the air may be
reduced. The ventilation fan suffers from reduction in the cooling
efficiency. As the printed circuit board gets thinner, the space is
reduced between the fan housing and the surface of the printed
circuit board. The cooling efficiency of the ventilation fan may
still get deteriorated.
SUMMARY OF THE INVENTION
[0006] It is accordingly an object of the present invention to
provide a printed circuit board unit with a cooling device
contributing to reduction in the thickness of an electronic
apparatus.
[0007] According to the present invention, there is provided a
printed circuit board unit with a cooling device, comprising: a
printed circuit board; a ventilation fan rotating around a rotation
axis intersecting the printed circuit board; a housing wall
standing from a surface of the printed circuit board at a periphery
of the ventilation fan; and an outlet defined in the housing
wall.
[0008] The printed circuit board and the housing wall cooperate to
define a space for accommodating the ventilation fan. When the
ventilation fan rotates, the movement of air, namely, airflow can
be generated within the space. The printed circuit board and the
housing wall lead the air toward the outlet. In this manner, the
printed circuit board can be utilized to form the cooling
device.
[0009] In particular, a high speed airflow can be generated within
the space in the printed circuit board unit and the housing wall.
The airflow efficiently absorbs the heat from the surface of the
printed circuit board. The heat radiation from the printed circuit
board can be promoted. In general, an electrically conductive
metallic wiring pattern extends over the surface of the printed
circuit board. The metallic wiring pattern usually has a superior
heat conductivity as compared with the material of the printed
circuit board. The metallic wiring pattern thus contributes to
promotion of the heat radiation from the printed circuit board. In
particular, the metallic wiring pattern inside the housing wall
leads to an improved promotion of the heat radiation from the
printed circuit board.
[0010] The printed circuit board unit of the aforementioned type
may further comprise: a ceiling wall connected to an upper end of
the housing wall and extending along a datum plane parallel to the
surface of the printed circuit board; and an inlet defined in the
ceiling wall.
[0011] In general, a number of electronic components are mounted on
the surface of the printed circuit board. The electronic components
protrude from the surface of the printed circuit board. The
electronic components is supposed to hinder a smooth flow of the
air along the surface of the printed circuit board. If the inlet is
defined at a position spaced from the surface of the printed
circuit board in the aforementioned manner, a smooth flow of the
air can be established irrespective of the existence of the
electronic components. The air can smoothly be sucked-into the
inlet. A large quantity of the air can be sucked, so that the
cooling efficiency of the cooling device can be improved.
[0012] For example, if the printed circuit board of the
aforementioned type is incorporated within an electronic apparatus,
the inlet can be opposed to the inner surface of the enclosure of
the electronic apparatus. Airflow can be generated along the inner
surface of the enclosure in response to the suction of the air into
the inlet. In general, a generally flat surface is defined on the
inner surface of the enclosure. Less obstacles can be found on the
inner surface of the enclosure as compared with the surface of the
printed circuit board. A smooth airflow can thus be generated along
the inner surface of the enclosure. The air is smoothly sucked into
the inlet. Since the air is smoothly introduced into the inlet in
this manner, a higher cooling efficiency can be kept even when the
space is reduced between the inlet and the inner surface of the
enclosure in the electronic apparatus. The thickness of the
electronic apparatus can reliably be reduced.
[0013] The printed circuit board unit of the aforementioned type
may further comprise an inlet defined in the printed circuit board
inside the housing wall. Air can be introduced not only from the
space adjacent the front side of the printed circuit board but also
from the space adjacent the back side of the printed circuit board.
A larger quantity of air can be sucked into the space defined by
the printed circuit board and the housing wall, so that the cooling
efficiency of the cooling device can further be improved. Moreover,
the front and back sides of the printed circuit board can
simultaneously be cooled down enough. It should be noted that the
inlet in the printed circuit board may be established in place of
the inlet in the ceiling wall. This structure contributes to a
further reduction in the thickness of the electronic apparatus.
[0014] In addition, the printed circuit board unit of the
aforementioned type may further comprise: an electronic component
mounted on the printed circuit board; and an electrically
conductive wiring pattern extending over the surface of the printed
circuit board inside the housing wall and connected to the
electronic component. The ventilation fan serves to promote the
heat radiation from the electrically conductive wiring pattern. The
heat radiation from the printed circuit board can still be
improved. Moreover, since the electrically conductive wiring
pattern is allowed to receive the heat from the electronic
component, the electronic component can efficiently be cooled
down.
[0015] A heat radiation fin may be attached to the printed circuit
board and connected to the electronic component. The heat radiation
fin promotes the heat radiation from the electrically conductive
wiring pattern. The heat radiation fin may be located within the
outlet. Alternatively, the heat radiation fin may be located to
face the outlet.
[0016] An electronic component may be mounted on the printed
circuit board inside the housing wall. A high speed airflow can be
generated inside the housing wall based on the rotation of the
ventilation fan in the aforementioned manner. Accordingly, the
electronic component can efficiently be cooled down. The electronic
component may be located within the outlet, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The above and other objects, features and advantages of the
present invention will become apparent from the following
description of the preferred embodiment in conjunction with the
accompanying drawings, wherein:
[0018] FIG. 1 is a perspective view schematically illustrating a
notebook personal computer according to an example of an electronic
apparatus;
[0019] FIG. 2 is a plan view schematically illustrating the inner
structure of a main body and the front surface of a printed circuit
board unit;
[0020] FIG. 3 is an enlarged plan view schematically illustrating
the back surface of the printed circuit board unit;
[0021] FIG. 4 is an enlarged plan view of a printed circuit board
for schematically illustrating the main portion of a cooling device
according to a first embodiment of the present invention;
[0022] FIG. 5 is an enlarged partial sectional view taken along the
line 5-5 in FIG. 2;
[0023] FIG. 6 is an enlarged partial sectional view, corresponding
to FIG. 5, for schematically illustrating a modification of the
cooling device;
[0024] FIG. 7 is an enlarged plan view, corresponding to FIG. 4,
for schematically illustrating the structure of a cooling device
according to a second embodiment of the present invention; and
[0025] FIG. 8 is an enlarged plan view, corresponding to FIG. 4,
for schematically illustrating the structure of a cooling device
according to a third embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] FIG. 1 illustrates a notebook personal computer 11 as an
example of an electronic apparatus. The notebook personal computer
11 includes a thin main body 12 and a display enclosure 13 coupled
to the main body 12. The display enclosure 13 is allowed to swing
relative to the main body 12. Input devices such as a keyboard 14
and a pointing device 15 are embedded in the surface of the main
body 12. The user may utilize the keyboard 14 and the pointing
device 15 so as to manipulate the notebook personal computer
11.
[0027] A liquid crystal display (LCD) panel module 16 is
incorporated within the display enclosure 13, for example. The
screen of the LCD panel module 16 is positioned in a window 17
defined in the display enclosure 13. The user is allowed to observe
the operation of the notebook personal computer 11 based on texts
and graphics, for example, displayed on the screen of the LCD
display panel module 16. The display enclosure 13 may be superposed
over the upper surface of the main body 12 through the swinging
movement.
[0028] As shown in FIG. 2, a printed circuit board unit 18 is
incorporated within the main body 12. The printed circuit board
unit 18 includes a printed circuit board 19 and a central
processing unit (CPU) package 21 mounted on the front surface of
the printed circuit board 19, for example. The CPU package 21 may
include a small-sized ceramic substrate 22 and a CPU chip 23
mounted on the ceramic substrate 22, for example. Not only the CPU
package 21 but also various electronic components 24a, 24b are
mounted on the front surface of the printed circuit board 19. An
electrically conductive wiring pattern, not shown, is formed to
extend over the front surface of the printed circuit board, for
example. The electrically conductive wiring pattern serves to
establish electric connections between the CPU package 21 and the
electronic components 24a, 24b as well as between the electronic
components 24a, 24b.
[0029] Within the main body 12, a secondary battery 25 as well as a
hard disk drive (HDD) 26 is connected to the printed circuit board
unit 18, for example. The secondary battery 25 and the HDD 26 may
be detachably incorporated within the main body 12. The secondary
battery 25 supplies an electric power to the printed circuit board
18 in place of an AC power supply, for example. The HDD 26 is
allowed to hold application software programs to be processed at
the CPU chip 23 as well as various data utilized during the
execution of the application software programs.
[0030] A cooling device 27 according to a first embodiment of the
present invention is coupled to the CPU package 21. The cooling
device 27 includes a heat receiving plate 28, of a higher heat
conductive material, superposed on the upper surface of the CPU
chip 23. One end of a heat conductive member such as a heat pipe 29
is connected to the heat receiving plate 28. The other end of the
heat pipe 29 is connected to heat radiation fins 31 attached to the
printed circuit board 19. Heat of the CPU chip 23 is transmitted to
the heat radiation fins 31 via the heat receiving plate 28 and the
heat pipe 29. The heat radiation fins 31 are allowed to protrude,
out of a recess 32 defined in the printed circuit board 19, into a
space at the back of the printed circuit board 19.
[0031] As shown in FIG. 3, electronic components such as a memory
module 35 including a random access memory (RAM), a PC card slot
36, a local area network (LAN) module 37 are mounted on the back
surface of the printed circuit board 19. In this manner, relatively
taller electronic components are mounted on the back surface of the
printed circuit board 19 as compared with the front surface.
[0032] A fan unit 38 is further incorporated within the cooing
device 27. The fan unit 38 is attached to the back surface of the
printed circuit board 19, as shown in FIG. 3. The fan unit 38
includes a fan housing 39 fixed to the back surface of the printed
circuit board 19. A top or ceiling wall 41 is defined in the fan
housing 39. The ceiling wall 41 is allowed to extend along a datum
plane parallel to the back surface of the printed circuit board 19.
An inlet 42 is defined in the ceiling wall 41. The inlet 42 serves
to interconnect the space inside the fan housing 39 and the space
outside the fan housing 39 to each other.
[0033] Referring also to FIG. 4, a rotary member 43 is accommodated
within the fan housing 39. The rotary member 43 is designed to
rotate around the rotation axis CR extending in a direction
perpendicular to the back surface of the printed circuit board 19.
Blades 44 are integrally formed on the peripheral surface of the
rotary member 43. The blades 44 may be located at equal intervals,
for example. The respective blades 44 are designed to extend in the
centrifugal directions from the rotary member 43. The individual
blade 44 extends in a plane intersecting, by a predetermined
inclination angle .alpha., the vertical plane VP including the
rotation axis CR. When the rotary member 43 rotates, the blades 44
serve to generate airflow in the centrifugal direction from the
rotation axis CR. The rotary member 43 and the blades 44 constitute
a so-called fan or ventilation fan.
[0034] As is apparent from FIG. 4, a housing wall 45 is defined in
the fan housing 39. The housing wall 45 is designed to stand
upright from the back surface of the printed circuit board 19 at
the periphery of the blades 44, so that the housing wall 45 mostly
surrounds the ventilation fan. Specifically, the inner surface of
the housing wall 45 is opposed to the outer ends of the blades 44
at positions spaced from the outer ends of the blades 44. An outlet
46 is defined in the fan housing 39 at the break of the housing
wall 45. The outlet 46 is located to face the heat radiation fins
31. An inlet 47 is also defined in the printed circuit board 19
inside the housing wall 45. The inlet 47 likewise serves to
interconnect the space inside the fan housing 39 and the space
outside the fan housing 39 to each other, in the same manner as the
aforementioned inlet 42. Part of the printed circuit board 19
constitutes the fan housing 39.
[0035] As is apparent from FIG. 5, the rotary member 43 is mounted
on a rotary shaft 51 extending in the vertical direction
perpendicular to the back surface of the printed circuit board 19.
The rotary shaft 51 is received on a bearing 52 fixed to the
ceiling wall 41 of the fan housing 39. A thin electric motor 53 is
interposed between the rotary member 43 and the bearing 52. The
electric motor 53 may include permanent magnets 54 attached to the
rotary member 43, and stationary coils 55 fixed to the bearing 52
and opposed to the permanent magnets 54. A controller board 56 is
also fixed to the ceiling wall 41 of the fan housing 39. A
controller circuit is established on the controller board 56. The
controller circuit operates to control the operation of the
electric motor 53.
[0036] Now, when an electric power is supplied to the electric
motor 53, the rotary member 43 rotates around the rotation axis CR.
The blades 44 generate airflow in the centrifugal direction of the
rotation axis CR. The generated airflow is guided along the housing
wall 45 to the outlet 46. The air is discharged out of the outlet
46 in this manner.
[0037] An opening 58 is defined in an enclosure 57 of the main body
12. The opening 58 is located to face the outlet 46 of the fan unit
38. The air discharged out of the outlet 46 is allowed to flow
through the heat radiation fins 31 and gets out of the main body 12
through the opening 58. The air absorbs the heat from the heat
radiation fins 31. In this manner, the heat radiation from the heat
radiation fins 31 is efficiently promoted.
[0038] A high speed airflow is generated based on the rotation of
the blades 44 within the inner space surrounded by the printed
circuit board 19, the housing wall 45 and the ceiling wall 41. The
airflow efficiently absorbs the heat from the surface of the
printed circuit board 19. The heat radiation from the printed
circuit board 19 can be promoted. In general, an electrically
conductive metallic wiring pattern extends over the surface of the
printed circuit board 19. The metallic wiring pattern usually has a
superior heat conductivity as compared with the material of the
printed circuit board 19. The metallic wiring pattern thus
contributes to promotion of the heat radiation from the printed
circuit board 19. In particular, the metallic wiring pattern inside
the housing wall 45 leads to an improved promotion of the heat
radiation from the printed circuit board 19.
[0039] While the air is discharged out of the outlet 46 in the
aforementioned manner, air is sucked into the fan housing 39
through the inlet 42. Since the inlet 42 in the ceiling wall 41 is
opposed to the inner surface of the enclosure 57, airflow 61 can be
generated along the inner surface of the enclosure 57 in response
to the suction of the air into the inlet 42. In general, a number
of electronic components are mounted on the back surface of the
printed circuit board 19. The electronic components protrude from
the back surface of the printed circuit board 19. The electronic
components thus hinder a smooth flow of the air along the back
surface of the printed circuit board 19. On the other hand, a
generally flat surface is defined on the inner surface of the
enclosure 57 of the main body 12. Less obstacles can be found on
the inner surface of the enclosure 57. The smooth airflow 61 can be
generated along the inner surface of the enclosure 57 of the main
body 12. The air is smoothly sucked into the inlet 42. A large
quantity of the air can be sucked into the fan housing 39, so that
the cooling efficiency of the fan unit 38 can be improved. Since
the air is smoothly introduced into the inlet 42 in this manner, a
higher cooling efficiency can be kept even when the space is
reduced between the ceiling wall 41 of the fan housing 39 and the
inner surface of the enclosure 57.
[0040] At the same time, air can be sucked from the inlet 47 in the
printed circuit board 19 in the fan unit 38. The air is introduced
into the fan unit 38 not only from the space adjacent the back
surface of the printed circuit board 19 but also from the space
adjacent the front surface of the printed circuit board 19. A still
larger quantity of the air can be sucked into the fan housing 39,
so that the cooling efficiency of the fan unit 38 can further be
improved. Moreover, the front surface of the printed circuit board
19 can be cooled down enough even when the fan unit 19 is located
on the back surface of the printed circuit board 19.
[0041] When the inlet 47 is defined in the printed circuit board 19
in the aforementioned manner, the ceiling wall 41 of the fan
housing 39 may completely superposed over the inner surface of the
enclosure 57, as shown in FIG. 6. Air can be sucked enough into the
fan housing 39 from the inlet 47 irrespective of the closure of the
inlet 42. A sufficient cooling efficiency can be maintained in the
fan unit 38. This structure is supposed to contribute to an
additional reduction in the thickness of the main body 12.
[0042] FIG. 7 illustrates a cooling device 62 according to a second
embodiment of the present invention. The cooling device 62 includes
an electrically conductive wiring pattern 63 extending over the
front surface of the printed circuit board 19, and heat radiation
fins 64 attached to the front surface of the printed circuit board
19. The electrically conductive wiring pattern 63 is connected to a
power consumption circuit, namely, the CPU package 21 and to the
heat radiation fins 64. Soldering may be employed to fix the heat
radiation fins 64 to the electrically conductive wiring pattern 63
on the printed circuit board 19. The electrically conductive wiring
pattern 63 may function as a ground wire of the CPU package 21. It
should be noted that like reference numerals are attached to the
structure or components equivalent to those of the aforementioned
first embodiment.
[0043] A fan unit 38a is attached to the front surface of the
printed circuit board 19 in the cooling device 62. The fan unit 38a
may have the structure identical to that of the fan unit 38
according to the first embodiment. The heat radiation fins 64 may
be located within the outlet 46 of the fan unit 38a, for example.
In addition, the electrically conductive wiring pattern 63 is
allowed to extend from the CPU package 21 to the heat radiation
fins 64 inside the housing wall 45.
[0044] The cooling device 62 induces the heat radiation of a higher
efficiency from the printed circuit board 19 based on a high speed
airflow generated within the fan housing 39 of the fan unit 38a in
the same manner as described above. The electrically conductive
wiring pattern 63 promotes the heat radiation from the printed
circuit board 19. In addition, since the electrically conductive
wiring pattern 63 is allowed to efficiently receive the heat from
the CPU package 21, the CPU package 21 can efficiently be cooled
down.
[0045] The air discharged from the outlet 46 is allowed to pass
through the heat radiation fins 64. The air absorbs the heat from
the heat radiation fins 64. The air thereafter gets out of the
enclosure 57 of the main body 12 from the opening 58. The heat
radiation from the heat radiation fins 64 can thus be promoted.
Otherwise, any electrically wiring pattern for the ground of the
electronic components 24a, 24b may likewise be connected to the
heat radiation fins 64.
[0046] FIG. 8 illustrates a cooling device according to a third
embodiment of the present invention. The cooling device 66 likewise
includes the aforementioned fan unit 38. Electronic components 67
are mounted on the back surface of the printed circuit board 19
inside the housing wall 45 in the fan unit 38. The electronic
components 67 may be located at the outlet 46 of the fan unit 38,
for example. The cooling device 66 of this type serves to promote
the heat radiation from the electronic components 67 based on a
high speed airflow generated within the fan housing 39 of the fan
unit 38 in the same manner as described above. It should be noted
that like reference numerals are attached to the structure or
components equivalent to those of the aforementioned first
embodiment.
[0047] The printed circuit board unit 18, along with the cooling
device 27, 62, 66 may be incorporated not only in a portable
electronic apparatus such as the aforementioned notebook personal
computer 11 and a personal digital assistant (PDA) but also in a
desktop type electronic apparatus. The bearing 52 for the rotary
shaft 51 may be supported directly on the printed circuit board 19
in the fan unit 38, 38a.
* * * * *